The purpose of the proposed study is to investigate the neural regulation of the onset of puberty. It is hypothesized that during the onset of puberty the electrical activity of certain cell populations in the brain: the arcuate-median eminence (ARC-ME), the preoptic area (POA), and the amygdala (AMY) responsible for the release of gonadotropin-releasing hormone (GnRH) are altered not only with respect to their individual electrical activities, but also with respect to how their electrical activities relate to one another. To test this hypothesis, the electrical activity of three areas of the brain, ARC-ME, POA, and AMY will be simultaneously recorded during the onset of puberty in normal female rats and during the estrous cycle in adult rats. These primary data are analyzed by cross correlation analysis, a sophisticated mathematical technique which measures the relationships between two signals, e.g., direction and temporal sequence of electrical signal flow, feedback, and hidden pulses and periodicities in noise. By use of this technique it is possible to assess how electrical signals in the AMY, ARC-ME, and POA interact near the time of puberty and relate them to changes seen in these areas in the adult cycling rat. We will also determine if any observed changes seen in the rat going through puberty can be shifted in time by electrical stimulation of the AMY.